One of the most important things to any parent is how they will provide a college education to their children. If you have been putting money away into your child's 529 plan over the years while you were married, a divorce will force you and your spouse to decide what to do with this savings plan.
You have a couple of options, one of which is to have one parent assume individual control of the plan after both parties mutually agree to it. In many cases it makes sense to give control to the non-custodial spouse so that the 529 savings plan isn't considered on your child's FAFSA.
Another option if you are worried about your spouse potentially removing funds from the account is to freeze the plan. This would mean no funds could be added to the account and the only way to withdraw money is if it is going to be used to pay for the child's education.
A third option is to split the savings into two separate 529's, each in one of the parents' names. Each account can continue to receive deposits towards your child's college education and the spouse who owns it would have full control over how to invest it.